I can provide some comparison for you, as I just got DC Lewis Porters off the B&S and also have a narrow foot. In general, I'd say the DC Lewis on the 101 last fit true to size lengthwise, and are narrower than most width-wise.
For comparison, I measure an arch length between 11 and 11.5 C on a Brannock. Keep in mind the important measurement on a Brannock device (at least IMO) is the arch length slider, which measures your arch length from the ball of the foot to the heel. By the length indicator on the Brannock I'm close to a 12, but I've never bought a 12 that fit in my life. Toe boxes are longer today, so the overall length measurement on a Brannock is of little value (again, IMO)
Anyway, the following shoes, in my experience, fit about like the DC Lewis 101:
Lobb 7000 last in 10E is about the same length, but significantly wider. Same for The 8000 last in 10.5 E.
Alden Barrie in 10.5 C is about the same width, same arch length, shorter toe box.
Alden Aberdeen in 11D is a touch wider.
Corthay Arca 11 D is longer and wider. I know people report these shoes to be very narrow, but that was not my experience. I probably needed a 10.5 in the Arca.
EG size 10.5 E on the 888 is similar in length and width. Maybe I'm crazy, but the EGs seem slightly wider, or at least seem to have more volume in the instep.
Allen Edmonds "0" last (Evanston) in 11C is about the same as the DC Lewis 11D.
Other impressions (in case you are interested): The shoes are a good deal in this price point. I think the last is quite elegant, and is more of what you'd see on higher dollar shoes. I think most other brands in this price range are intended for a more mass market, and thus are more conservative. In that sense, you get something from DC Lewis style-wise that might otherwise be tough to find. Construction is very good, though I don't see the "extensive" handwork mentioned in other posts/threads. Caveat: Im not even sure what that means in the shoe context anyway - if you are running the shoe through a sewing machine by hand, is it handwork? My grandfather was a tailor, he and my grandmother did all the sewing themselves, and yet they used machines whenever possible. Still his stuff was unequivocally "handmade" but only the buttonholes, sleve attachment, and a few other things were "handwork.". So assuming handwork means "sewn by hand" I don't see it, and I can usually tell the difference.
IMO construction is superior to Alden - though I am notorious for bitching about Alden's uneven quality, and I've only seen one pair of DC Lewis. On average, across many shoes, Alden might be better (but I doubt it).
Materials I'm not so impressed with - the uppers seem fine for this price range - comparable to C&J, better than AE. Hard to compare with Alden since their leather is all over the place. Generally, I'd say Alden's leather is slightly higher quality. Soles seem very "light" for goodyear welted shoes - just not all that substantial. The beveled waist / fiddle back is pretty rough hewn. On the other hand, you don't normally see that feature on shoes in this price range.
Overall it's a pretty lightweight shoe, which makes me wonder where the missing ounces come from. We'll see how they wear.
Overall, I'd say DC Lewis is a very solid value in this price range. Style-wise, you will find very little that's comparable. Construction wise, they compare favorably. Materials-wise, they run with the pack. I'll be buying more, provided they don't completely fall apart in a few months.